1. Field of the Invention
The present invention relates to a photomask, and more particularly, to a photomask with photoresist test patterns and a pattern inspection method.
2. Description of the Prior Art
In the current lithography process, a stepper is used to perform photomask pattern transfer in order to obtain an image with high resolution and better particle tolerance. However, the main problem of this method is that a wafer needs to be exposed separately in order to complete the fabrication of a single patterned layer. Exposure needs to be performed several times in order to finish one single patterned layer. In order to ensure that the patterns between the layers are stacked accurately, layers of photoresist material can be inspected following development (after-develop-inspection or “ADI”) to ensure that the pattern transfer process has been performed correctly and/or that the pattern is within specified tolerances. From such inspection, mistakes or unacceptable process variations associated with the layer of photoresist material can be identified and corrected. However, from this inspection, the patterned exposure status of the first layer can not be monitored, thereby resulting in mistakes associated with the patterned exposure of the first layer being undefectable. Further, it wastes processing time and increases cost.
In the view of this, the present invention provides a photomask with photoresist test patterns and a pattern inspection method, which eliminates misalignment errors of the first layer of photomask in step exposure to effectively overcome the problems that exist in the prior art.